The present invention relates to a dual-track chassis, and more particularly to a dual-track chassis of the type wherein an understructure carries a load which is pivotal about a vertical axis with respect to the understructure, the understructure being supported at two oppositely disposed points of support on each track and on a rocker member which, in the normal position (that is, when the chassis is on a flat surface), is parallel to a line between the two points of support and is rotatable about an axis lying in the vertical longitudinal center plane of the chassis. Each end of the rocker member is supported in a respective crawler member, and the distance of the axis of rotation from the rocker member is greater than the distance between the rocker member and the vertical axis.
In a prior art dual-track chassis which includes an understructure, a pair of crawler members, and a rocker member, a surface-mining apparatus (such as a bucket wheel excavator, putting-down equipment, or the like) is disposed on the understructure so as to be pivotal about a vertical axis. The understructure is supported on both sides by the associated crawler members so as to be tiltable in a plane extending through the vertical axis and transversely to the direction of travel. The rocker member is rotatably mounted at one end of the understructure and permits oppositely directed tilting of the two crawler members. Each end of the rocker member is supported in the associated crawler member by a spherical joint and so as to be longitudinally displaceable. In this prior art dual-track chassis, although the load is supported at three points--i.e. as determined statically--its stability is insufficient in many cases, particularly if the load is displaced into an extremely off-center position.
It has therefore been proposed, in such a dual-track chassis, to keep the distance between the axis of rotation and the rocker member greater than the distance between the rocker member and the vertical axis about which the load is pivoted, as disclosed for example in German Offenlegungsschrift (unexamined, published application) 2,536,652, which relates to a dual-track chassis of the same species. However, with such an arrangement of the axes, problems arise which can only be overcome by providing for a special position and configuration of the load supporting point in the chassis carriers as described in detail in the cited publication.